The medium-term results of treatment with hydroxyapatite implants.

Although the short-term results of implants with synthetic hydroxyapatite (HA), a bioactive material, have been favorable, few reports have been published concerning medium-term outcomes for this therapy. The authors recently analyzed data supplied by 37 medical facilities nationwide concerning the outcomes of synthetic HA implants [Bonfil (BF); Mitsubishi Materials Corporation, Tokyo] in 138 patients followed up for at least 5 years after treatment. When the data were analyzed, the patients were divided into two groups: the disease site-filling group (62 cases where bone defects created by disease were filled with synthetic HA) and the donor site-filling group (76 cases where bone defects created by bone donation were filled with synthetic HA). In the disease site-filling group, synthetic HA was used in combination with autologous bone or autogenous bone marrow donated from the same patient in 77% of cases. In the donor site-filling group, only synthetic HA was used in most cases. The average follow-up period after implantation was 7.9 years in the disease site-filling group and 9.1 years in the donor site-filling group. Therapy was rated radiographically as "very effective" or "effective" in 81% of patients in the disease site-filling group and in 89% of patients in the donor site-filling group. The therapy was not rated as "ineffective" in any case from either group. These results suggest that synthetic HA may serve as a very useful substitute for cancellous bone if used carefully, with its initial strength taken into account.